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101.
Luca Rolle Manuela Giordano Simone Giacosa Simone Vincenzi Susana Río Segade Fabrizio Torchio Benedetta Perrone Vincenzo Gerbi 《Analytica chimica acta》2012
In the oenological sector, the withering process is of particular importance in the production of dry and sweet dessert wines due to the total or partial use of overripe and/or dehydrated grapes. 相似文献
102.
S. Acquaviva G. Leggieri A. Luches A. Perrone A. Zocco N. Laidani G. Speranza M. Anderle 《Applied Physics A: Materials Science & Processing》2000,70(2):197-201
A hexagonal-BN target was ablated by high-fluence (6 and 12 J/cm2) KrF excimer laser pulses in low-pressure (5 Pa) N2 atmosphere, without any aid of ion bombardment and heating of the Si substrate. Investigations of the deposited films show that the cubic-BN phase was deposited. The film deposited at 6 J/cm2 appears to contain a higher cubic phase content with respect to the one deposited at 12 J/cm2. 相似文献
103.
D. Bernard F. Moulin F. Amiranoff A. Braun J.P. Chambaret G. Darpentigny G. Grillon S. Ranc F. Perrone 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2000,10(1):141-145
We have searched for stimulated photon scattering in vacuum at a center of mass photon energy of 0.8 eV. The QED contribution
to this process is equivalent to four wave mixing in vacuum. No evidence for scattering was observed. The corresponding upper limit of the cross-section is .
Received 29 September 1999 相似文献
104.
PTS, PM10 and PM2.5 samples have been collected at a rural site of south-east Italy (40 degrees 20' 13" N; 18 degrees 6' 47" E) from June to October, 2004 to investigate natural and anthropogenic contributions on particulate matter and heavy metal mass concentrations. It is shown that sharp-peak particulate-matter concentrations have been recorded during most African dust outbreaks occurred over south-east Italy. In particular, PM10 concentrations exceeding the 24-hour limit value of 50 microg/m3 have been monitored during dust events. Al, Cd, Cr, Cu, Fe, Mn, V, Ni, Pb, and Zn metal concentrations have been evaluated by an inductively coupled plasma atomic emission spectrometer and Al mass concentrations >500 ng/m3 have been observed in PTS and PM10 samples during the advection of African dust particles. Accordingly to geochemical calculations Al, Fe, and Mn, have a significant crustal origin while, Cd, Cu, Pb, and Zn are of anthropogenic origin. Moreover, Fe resulted predominant in the coarse particle fraction, while Ni, Pb, V, and Zn were predominant in the fine particle fraction. It is also shown that Cd, Mn, Ni, Pb, and V concentrations never exceeded guide and/or limit values recommended by the World Health Organization and the European Council Directives. 相似文献
105.
Domenico Perrone 《Mathematische Zeitschrift》2009,263(1):125-147
It is well known that a Hopf vector field on the unit sphere S
2n+1 is the Reeb vector field of a natural Sasakian structure on S
2n+1. A contact metric manifold whose Reeb vector field ξ is a harmonic vector field is called an H-contact manifold. Sasakian and K-contact manifolds, generalized (k, μ)-spaces and contact metric three-manifolds with ξ strongly normal, are H-contact manifolds. In this paper we study, in dimension three, the stability with respect to the energy of the Reeb vector
field ξ for such special classes of H-contact manifolds (and with respect to the volume when ξ is also minimal) in terms of Webster scalar curvature. Finally, we extend for the Reeb vector field of a compact K-contact (2n+1)-manifold the obtained results for the Hopf vector fields to minimize the energy functional with mean curvature correction.
Supported by funds of the University of Lecce and M.I.U.R.(PRIN). 相似文献
106.
Udaibir Singh Tikendra Prakash Singh Alessio Perrone 《Optics & Laser Technology》2010,42(7):1128-11421
In this paper the structure, morphology and optical properties of Pd thin films deposited on glass substrate by pulse laser deposition technique at two different substrate temperatures have been investigated. The fabricated films were characterized by various methods such as XRD, AFM, and UV-vis-NIR spectroscopy. The influence of surface roughness and angle of incidence with p polarization was investigated experimentally by optical property of palladium (Pd) thin films of two different thicknesses and rms roughness from transmission measurement in the visible spectral range. It has been shown that the experimental transmittance spectra agree well with their theoretical values for absorbing Pd thin film. The transmittance of thin film increases with increase in incident angle for the same sample. 相似文献
107.
Variational inference is a powerful framework, used to approximate intractable posteriors through variational distributions. The de facto standard is to rely on Gaussian variational families, which come with numerous advantages: they are easy to sample from, simple to parametrize, and many expectations are known in closed-form or readily computed by quadrature. In this paper, we view the Gaussian variational approximation problem through the lens of gradient flows. We introduce a flexible and efficient algorithm based on a linear flow leading to a particle-based approximation. We prove that, with a sufficient number of particles, our algorithm converges linearly to the exact solution for Gaussian targets, and a low-rank approximation otherwise. In addition to the theoretical analysis, we show, on a set of synthetic and real-world high-dimensional problems, that our algorithm outperforms existing methods with Gaussian targets while performing on a par with non-Gaussian targets. 相似文献
108.
[structures: see text] A general access to a novel class of sugar alpha-amino acids composed of iminofuranose and iminopyranose residues anomerically linked to the glycinyl group through an alkyl chain is described. A set of eight compounds was prepared by the same reaction sequence involving as an initial step the Grubbs Ru-carbene-catalyzed cross-metathesis (CM) of various N-Cbz-protected allyl C-iminoglycosides with N-Boc-vinyl- and N-Boc-allyloxazolidine. The isolated yields of the CM products (mixtures of E- and Z-alkenes) varied in the range 40-70%. Each mixture was elaborated by first reducing the carbon-carbon double bond using in situ generated diimide and then unveiling the N-Boc glycinyl group [CH(BocNH)CO2H] by oxidative cleavage of the oxazolidine ring by the Jones reagent. All amino acids were characterized as their methyl esters. The insertion of a model C-iminoglycosyl-2-aminopentanoic acid into a tripeptide via sequential carboxylic and amino group coupling with L-phenylalanine derivatives was carried out as a demonstration of the potential of these sugar amino acids in designed glycopeptide synthesis. 相似文献
109.
Broad band emission of KrF1 centered at about 400 nm was observed in various mixtures containing Kr and fluorinated compounds. This emission was resolved against the more intense Kr2F1 broad band emission at the same wavelengths due to its temporal behaviour and its different pressure dependence. Its radiative lifetime is 16 ns and it is tentatively ascribed to the 3 2∑+ → 1 2Π transition. 相似文献
110.
We consider a natural condition determining a large class of almost contact metric structures. We study their geometry, emphasizing that this class shares several properties with contact metric manifolds. We then give a complete classification of left‐invariant examples on three‐dimensional Lie groups, and show that any simply connected homogeneous Riemannian three‐manifold admits a natural almost contact structure having g as a compatible metric. Moreover, we investigate left‐invariant CR structures corresponding to natural almost contact metric structures. 相似文献